What is the best way to replace a 250 GB drive in my iMac (24" white)? I mean, I want to keep everything that is on it, so that I do not have to reinstall anything or lose anything. How do I, elegantly, transfer the data from one drive to another (bigger), including the OS (10.6.8.), without much risk and disruption? I do have another 250 GB back-up drive, using SuperDuper, btw.

Pardon me for being slow in this department, but how do I clone the old to new drive? At this moment, my back-up drive (250 GB) is encased. Do I have to open the case, replace it with a new drive (say 1 TB), use SuperDuper to clone the old to new, remove the new from the case, remove the old from the computer and put the 1 TB inside?

You'll have to have both drives mounted of course. Assuming the new drive is an internal, you'll need to find a goodie that allows you to mount it before you install (something like this:http://www.newertech.com/products/voyagerq.php)

OR if you have an external FireWire or similar drive, hook that up and clone the boot drive to that. Note you'll lose anything on that external drive. Then you can install new drive and format if necessary, boot off external and again, use SuperDuper to clone from external to new internal.

Can I do the following (seems simpler to me, no need to mount anything):

1. Check that my current back-up drive is up-to-date and capable of booting the computer2. Replace the old internal iMac drive with new3. Format the new drive (any need to partition Mac?)3. Use SuperDuper to clone the back-up drive to the new

For cloning: you could get one of these bare drive holders. I have two -- one at the office and one at home. They have proven to be very useful; for example, it's fairly painless to keep a cloned offsite backup drive at my office using this dock. Bring it home once a week, stick it in the dock, clone my iMac drive, take it back to the office.

Partitions: I've read several web sites suggesting that a scratch partition would speed up Photoshop, by my own testing on an iMac and Macbook Pro didn't show any real difference. The fastest scratch drive is just the main internal drive set up as a single partition (unless you can add a second drive on the SATA bus, which then does show an improvement.)

Can I do the following (seems simpler to me, no need to mount anything):

1. Check that my current back-up drive is up-to-date and capable of booting the computer2. Replace the old internal iMac drive with new3. Format the new drive (any need to partition Mac?)3. Use SuperDuper to clone the back-up drive to the new